An image forming apparatus includes a laser unit configured to emit a laser beam and a rotary polygon mirror configured to reflect the laser beam, which is emitted from the laser unit, to a photoconductive drum. The image forming apparatus exposes and scans the photoconductive drum according to the rotation and the reflection of the polygon mirror to form a latent image on the photoconductive drum, develops the latent image, and prints a developed image on an image formation medium.
If oscillation that occurs in the polygon mirror is large, distortion occurs in a printed image.